Swift4.0版-H5頁面實現長按保存圖片

• 剛開始拿到需求還是比較尷尬的,不會啊,沒做過啊,是不是就尷尬了
• 隨即想了一下,好像微信里好多H5頁面都有這樣的功能
• 然后查閱了一下相關資料,發現兩行核心代碼

//獲取長按所在點
let urlString = "document.elementFromPoint(\(touchPoint.x), \(touchPoint.y)).src"

//根據該點的參數獲取對應圖片的鏈接
let saveUrl = webView.stringByEvaluatingJavaScript(from: urlString)

下面來一起啊看一下完整的代碼步驟

首先給UiWebView加一個長按手勢

//添加長按手勢
let longPressGes = UILongPressGestureRecognizer(target: self, action: #selector(longPressedGesture(_:)))
//一定要遵循代理
longPressGes.delegate = self
webView.addGestureRecognizer(longPressGes)

實現代理方法

//不實現該代理方法,長按無效
//MARK: 手勢代理方法
extension SIWebViewController : UIGestureRecognizerDelegate{
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
}

接著在手勢響應方法里面實現相應的功能

注意:

• 一定要判斷手勢的state屬性
• 判斷saveUrl是否是一個nil值

@objc func longPressedGesture(recognizer: UILongPressGestureRecognizer){
    if recognizer.state != .began { return }
        
   let touchPoint = recognizer.location(in: webView)
    
    //核心代碼
    let urlString = "document.elementFromPoint(\(touchPoint.x), \(touchPoint.y)).src"
   if let saveUrl = webView.stringByEvaluatingJavaScript(from: urlString) {
        //判斷圖片的鏈接是否為空,長度是否為o
        if saveUrl.characters.count == 0 { return }
        addAlertAction(saveUrl)
    }
}

調用保存圖片功能按鈕

fileprivate func addAlertAction(imageStr: String){
        let alertV = UIAlertController()
        let saveAction = UIAlertAction(title: "保存圖片", style: .default) { (alertV) in
            self.saveImageToDisk(imageStr)
        }
        //取消保存不作處理
        let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
        
        alertV.addAction(saveAction)
        alertV.addAction(cancelAction)
        controller.present(alertV, animated: true, completion: nil)
}

使用SDWebImage保存圖片

• 注意使用SDWebImage的緩存機制

    //保存圖片
    fileprivate func saveImageToDisk(_ imageStr: String){
        guard let imageUrl = URL(string: imageStr) else { return }
        let sdManager = SDWebImageManager.shared()
        
        var image : UIImage!
        if (sdManager?.diskImageExists(for: imageUrl))! {
           //先從緩存中查找圖片
            image = sdManager?.imageCache.imageFromDiskCache(forKey: imageUrl.absoluteString)
        }else{
           //緩存中沒有圖片在進行網絡下載
            let data = try! Data(contentsOf: imageUrl)
            image = UIImage(data: data)
        }
        
        //保存圖片到相冊中
        UIImageWriteToSavedPhotosAlbum(image, self, #selector(self.image(_:didFinishSavingWithError:contextInfo:)), nil)
    }

最后是一個保存成功與否的回調方法

@objc func image(_ image: UIImage, didFinishSavingWithError: NSError?, contextInfo: AnyObject){
    if didFinishSavingWithError != nil {
        MBProgressHUD.show(string: "請開啟訪問相冊權限后使用此功能", inView: self.view)
    } else {
        MBProgressHUD.show(string: "圖片保存成功", inView: self.view)
    }
}

以上如有不妥之處還望多多指正